Control system



Jan- 8, 1946- E. M. SORENSEN 2,392,416

. CONTROL SYSTEM Original FildMay 16, 1940 .DE VICE CON T? 4 7' Toe/var- Patented Jan. 8,

Original application 11016.19, sem No. 335,517. Divided and this application January 8, 1941, Serial No. 373,819

BClaims.

(Granted under the act or March a, 1883,. as amended April so, 1928; 3'10 0. G. 751) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to .me of any royalty thereon.

This invention relates to control systems, and particularly to those systems in which the controlled device at the remote station is of a high-- iy sensitive character; for example, the relays which control the movements of an airplane and therefore respond to any deleterious condition found anywhere within the control circuit;

' Among such conditions, in case the controlling circuit employs tube amplifiers, is the variation of the filament supply potential which normally causes corresponding variations in the plate current. The present invention, therefore, more particularly relates to an improved system by which compensation is introduced to ofiset changes in electron emission brought about by variations in the filament supply potential. v

This is a division of my cOpending application Ser. No. 335,517, filed May 16, 1940, for Radio remote control system;

The primary object of the invention is to provide an emission compensator for tube circuits which find particular application iri'remotely controlled systems, and which give continuously variable operation of the control device and will be capable of energizing or utilizing any amount of power at the control device, regardless of the energy applied to the control. In systems of the character mentioned, for example in the control of an airplane which contains electro-responsiv'e devices extremely sensitive to the received signals and variations thereof, it is necessary that all causes by which deleterious electrical efiects are introduced into the system be eliminated. One

tentials. It is a known fact that when the filament temperature of an electronic tube is increased, a greater number of electrons is emitted from the filament. and vice versa a reduction in the filament temperature produces a decrease in the electron emission. This is true in connection with both vacuum and gas tube types, and also in those tubes which employ indirectly heated cathodes, because the temperature of the heater filament in that case bears a direct relation to the temperature or the cathode. The emission compensator disclosed in this application depends .for its operation on the use of the Edison eii'ect, and the potential changes set up from a diode plate to its cathode will vary with the temperature of 'the cathode. The manner in which this potential varies is controlled by the of the main defects resides in the manner of the V In the system shown inthe drawing there isillustrated a single-stage, amplifier which might form part of an intricately controlled system requiring a sensitive response to a controlling circuit, or apparatus which may be remotely or local- I! positioned and may involve a wire or radio linkcircuit. Thecircuit'isplrticularlyuseful in any amplifier where a great amount of starate at which the cathode heats up or cools oil, depending upon, the supply potential to the cathode.

The circuit comprises a diode tube I having .its plate 2 connected to the grid return 3 of the and cathode are commonly connected to ground,

or as shownto at H. l V

with this circuit the bias on the grid 4 will the-B supply terminal indicated I vary by measuring the bias from the grid 4 to the cathode I2 01' the triode tube 5 in a direct 4 relation with the filament potential as supplied to'the filamentaryheater, I4, assuming that the heater is supplied from the same potential which supplies the filament I5 01 the diode tube. The manner in which this bias potential varies follows very closely the value ot the voltage needed to bias the arid to maintain the plate'current oi the anode ii at the samervalue which was flowing prior to a change in at potential.

The battery! is poled as indicated, 1. e. its negativ terminal is connected to the cathode that the diode tube I. -Under these circumstancesitwmbenotedthatthe diodeplate i will have atpositive potential with reference to the cathode ll. Any changes incurrent being drawn by said diode tube will be represented by the voltage dro which takes place across the resistor 8. Thus it can be readily shown that r mm in p y 1 f rs vvalueotwmchtskes lac mm voltage as a bias voltage on the grid, especially 5 in ases where the emission of the tube varies a eat deal for a small filament potential change. By placing a potentiometer it in the return circuit of the cathode 12 a portion of any voltage variation across the filament circuit will also be represented on the grid. The potentiometer should be adjusted to provide the desired amount of bias voltage. Fixed resistances may be added to each side of the potentiometer, if necessary. This added bias voltage, together with the voltage asset up across the diode tube i, provides the necessary control to hold the plate current of the triod at a steady value for large changes infilament potential. These changes in filament potential may be as great as" 100 per cent. That is to say, for a tube which has a normal operating voltage of 6.3 volts, the filament supply voltage may vary from 4 to 8 volts with the emission remaining constant over this range. It may alsobe pointed out that this additional voltage may be'obtained from the plate supply voltage .in those cases where the plate supp voltage is obtained from the same source as the filament supply voltage, as any variation in the filament voltage willeaus'e' a variation in the plate supply voltage in the same proportion.

It is apparent that in any tube system in which the disclosed compensating circuit, is employed this circuit serves to render the current response of the tubes independent of filament voltage variation within-the range compensated, and reis very important when the filament voltage cannot be maintained constant, as would probably be the case in the power supply ofaircraft. In the event of a change in filament potential va-.

riation with'out provision for emissloncompensation in response to such change. a y relays which may be connected to the output. circuit of the tube 5 for controlling a motor circuit of the aircraft would be affected by changes in the g It will be understood that Idesire to comprehend within my invention such modifications as come within the scope of the claims and the invention.

' Having thus fully described my invention, what I claim as new and desire to secure by Letters- -Patent,is:

1. An electronic circuit for compensating for variation in emission of the cathode emitter ofan electronicvalve due to filament potential variation, said circuit comprising-a diode electronic tubehaving its anode in series with the grid return of said electronic valve and its filament potential supplied from the same source as the filament of the electronic valve, a circuitincludlng a battery and a: resistance connecting the grid return of said electronic valve to the cathode of sponsive only to the signal applied to'the grids of those tubes from an external source. This.

- means for preventing variations of potential ofsaid diode tube, said battery being arranged with its negative pole toward said cathode and said resistance being intermediate ,said battery and said grid return, the valuesof said battery, resistance and said diode tube being such that the potential between said grid return point and-the junction of said battery and cathode is equally divided across said diode tube and said battery circuit.

2. In an amplifying system which includes a tube of the indirectly heated typ a plate, a control grid, a cathode, a filamentary heater for said cathode contained in said tube, a source of ener y forenergizing said filamentary heater, 7

and means for preventing variations in the potential of said source of energy from afi'ecting the plate current, said means comprising a rectifier connected between. the cathode and the control grid, said rectifier having a filamentary cathode which is energizedfrom the same source as the filamentary heater of said tube.

3. In an amplifying system, a tube containing.

a cathode, control grid and plate, said' cathode being activated -from a source of energy, and means for preventing potential variations of said source from deleteriously afiecting the plate current, said means comprising a rectifier having an anode, an indirectly heated cathode and a filamentary heater for the last-mentioned cathode, said anode being connected to the control grid of the amplifier and said filamentary heater being connected to said source of energy, and said indirectly heated cathode being connected to the cathode of said amplifier.

4. In an amplifying system, atube containing a cathode, control grid and plate, said cathode being activated from a source of energy, and means for preventing potential variations of said source from deleteriously affecting the plate current, said means comprising a rectifier having-an anode, an indirectly heated cathode, a filamentary heater for the last-mentioned cathode, said anode being connected to the control grid of the amplifiensaid filamentary heater being connected to said source of energy, said indirectly heated cathode being connected to the cathodeofsaid amplifier, and a biasing potential connected 'between the plate of the rectifier and its cathode.

5. In an amplifying circuit, a tube including an anode, control grid, indirectly heated cathode and afilamentary heater therefor, said heat--. er being connected to a source of current, and

said source from deleteriously afie'cting'the plate current. said means comprising a resistor connected across the legs of the filamentary heater and an adjustabletap taken from the-resistor to the indirectly'heated cathode, said means also including a rectifier connected between the indirectly heated cathode and the control grid, said rectifier. having a filamentary member which is connected to said source of current and subject tothe same potential variations which aifect the amplifier tube, and an anode in said rectifier tube connected through. a resistor ;to the control 7 grid of the amplifier tube and biased positive with respect to the-filament of the rectifier tube.

6. In an amplifying. circuit, a tube including an anode, control grid, indirectly heated cathode and-a filamentaryheatertherefor, said heat- 7 nected across the legs'of the filamentary heater and an adjustable tap taken from the resistor in the indirectly -heated cathode said means also including a rectifier connected between the indirectly heated cathode and the control grid, said rectifier having an anode, an indirectly heated mentary heater of the amplifier tube, the indirectly heated cathode of said rectifier tube being connected directly to the filamentary heater of the amplifier tube, the anode of said rectifier tube being biased positive with respect to the cathode of the rectifier tube and connected to the control grid ot the amplifier tube.

EDWARD- M. SORENSEN. 

